Although specialized systems-on-chip have taken over most high-volume embedded applications, licensable CPU cores top out at about 400 MHz. That leaves a sizable market for general-purpose processors using custom CPUs; we estimate that these embedded processors generated more than $1 billion in 2003 revenue.
The leading vendor of general-purpose embedded processors is Intel. Leveraging its PC and server processors, Intel serves many embedded applications: industrial control, interactive kiosks, ATMs, point-of-sale terminals, PBXes, media servers, storage servers and security appliances.
In most cases, individual systems in those categories have limited volume, so reducing design cost is important. A PC or server platform simplifies hardware design, particularly if a standard motherboard or single-board computer is used. Software can be developed and tested on a standard PC, further reducing R&D. The high volume of PC processors and chip sets drives down the price for embedded buyers.
Not just Intel
Seeing these advantages, other X86 vendors have jumped into the embedded market. Earlier this year, Advanced Micro Devices announced an embedded version of Athlon, called Geode NX, and Transmeta offers an embedded Crusoe processor. Via Technologies sells more of its X86 chips into embedded applications than into PCs. Those vendors have a long way to go to catch up to Intel's revenue, however.
Embedded X86 processors have some disadvantages. Because they must perform well with legacy software, X86 CPUs use translation, reordering and renaming. Those complex schemes burn extra power but are generally unneeded in an embedded system, where software can be recompiled for the target CPU.
The processors also lack integrated peripherals and must be connected to system-logic chip sets that are optimized for PCs or servers, not embedded systems. As a result, the chip sets take up extra board space and consume more power.
For example, PMC-Sierra's 1-GHz RM9150 requires less power than a 1-GHz Geode or 1-GHz Crusoe, even though the MIPS chip includes a 3.2-Gbyte/second DRAM controller, 64-bit PCI interface, HyperTransport port, two Gigabit Ethernet MACs and other peripherals. Intel's Pentium-M uses the same power as the RM9150 only because it is built in Intel's advanced 90-nanometer technology.
Most networking and consumer applications have strict limits on heat and board space. These routers, printers and set-top boxes generally rely on RISC processors. But for a variety of PC-like applications, embedded X86 processors from Intel and others provide a simple, low-cost solution.
Linley Gwennap is founder and principal analyst of The Linley Group and co-author of “A Guide to High-Speed Embedded Processors” (www.linleygroup.com/npu).